Process of making nitric acid from air.



PATENTED MAR. 13, 1906.

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PROCESS OF MAKING NITRIC AUID F3935 AIR.

APPLIOATZON FILED MAE-24, 1904;.

W/TMESSES: $2

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ARTHUR Rail-LING AND HARRY PAULING, OFBISMARCK, GERMANY; ASSIGNORS TO THE FIRM OF CHEMISCHE FABRIKEN GLADBECK, GESELLSCHAFT MIT BESUHRANKTEB HAFTUNG, 0F GLADBECK,

GERlViANY.

FPEGGESS QF MAKING NlTFlli) ZACH? AER Specification of Letters Eatent.

'latented March 13, 1908.

' Applicatioufiled March 24,19Ue. Serial No. 199,860-

The process depends upon the Well-known i fact that air on being heated to at least 1200 centigrade is partially converted into one or more of the oxide of nitrogen. The extent of conversion increases with the temperature according to the well-known equation of the roaciion-isochor. At 1 700 centigrade, for instance, the quantity oi nitric oxid or other nitrogen oxid amounts to about three per cent. according to recent determinations. Although in prior experiments on the production of nitric acid from air the latter has undoubtedly been heated to the temperature stated and even to a still higher degree, the results obtained have not been satisfactory, since it has not been possible to successfully separate the nitrogen oxid from the air. The

essential fault of prior methods has been that the highly-heated air has cooled down again gradually, in consequ nce of which the above mentioned process of conversion has been reversed, which, indeed, follows naturally from the equation of the reaction-isochor, which is only applicable to reversible processes. According to our invention this defect has been entirely overcome.

In carrying out our process We heat the air or other mixture of oxygen and nitrogen to a very high temperature and then at once chill or cool the resulting nitrous products in the immediate proximity of the place of maximum heating, this cooling being, cllcctcd s) rapidly that reversal of the process of conversion is prevented, so that the nitric oxid or other oXlds of nitrogen cannot be decomposed again. l'Vatcr-yapor is then supplied for the purpose of producinq nitric acid. The

coolh'lg or chilling can be cll'ected by cooled metallic or other surfaces or by the injection.

of cold, indifferent, or neutral liquids or gases or in any other suitable manner. The essential point is that the cooling be effected more rapidl than the oxids of nitrogen which have been formed are decomposed again owing to reversal of the process. 7

The accompanying drawings illustrate three dili'erent arrangements of appratus suitable i or carrying our invention into ellectn Figure l is a vertical section of one form of apparatus suitable for the object in view. Fig. 2 is a sectional view illustrating a second arrangement which may be adopted. Fig. 3 is a like view illustrating a third arrangement.

Referring to Fig. 1, 1 is a fan by means of which air or some other mixtures of oxygen and nitrogen is forced through a con'server or accumulator of heat 2, previously heated to the desired temperature. The air (or other gaseous mixture) leaves the vessel .2 with great velocity at the outlet and meets the conical jet 4 of" atomized cold Water issuing rom the tank 5. The water jet 4 is immediately converted into steam, and owing to the high degree of absorption of heat (latent heat and heat required to heat the Water and steam) the air (or other mixture) is cooled below the' injurious limit of temperature. The cooled mixture of air and steam leaves the apparatus at the exit 6 for the purpose of further cooling and condensation of the acid vapors formed.

Referring now tothe second arrangement, as shown in Fig. 2, 7 is an alternati1'1g-cur rent are T, which may advantageously be of about two inches in length. Usually such an arc has a more or less conical shape, as shown by the dotted lines in Fig. 2. The part 7 (hatched lines, Fig. 2.) forms the actual path 1' zone of the current between the electrodes and ill, and thus constitutes the source of heat, While the part 8 represents the air heated by the part 7 and under ordinary circumstances ascendii'ig in the shape of a .cone. 1 i represents tubes cooled by Water or other means located directly above the zone 7, wherebv the formation of the par 8 of the electric arc, such 'would ordinarily occur,- is prevented. The port 5, as a matter of fact, merely indicmvs that the air highly 

